Why did you get a headache after safely looking at the eclipse?

SPOKANE, Wash. - After decades of waiting, the total solar eclipse was over within hours, but it still had the potential to cause lifelong problems for your vision.
The Spokane Eye Clinic says only a few people have made appointments because they're worried about eye damage, but many others felt another kind of pain. Headaches. Some people tied those headaches directly to the eclipse.
The eclipse caused a lot of noticeable changes, like a cooling in the temperature and things got a little darker. But some say they experienced more.
"It felt like the air was really close and dense. I just started feeling really different," said Spokane resident Hollie Eastman.
Eastman said she had a headache that persisted the entire morning of the eclipse. And she's not alone. On the KXLY 4 News Facebook page, dozens of comments from our viewers reported the same thing: a headache brought on by the eclipse, then fading when the astronomical event ended.
"I'm glad to know I'm not alone though. It doesn't surprise me, but I felt kind of strange," Eastman said.
If you experienced one of those headaches, you probably don't have to worry about long-term effects. Medical professionals say it was likely just caused by eye strain, brought on by staring at the sun for an extended period of time, being outside for hours and wearing uncomfortable cardboard glasses.
Thankfully, most people wore those glasses. The Spokane Eye Clinic says it was prepared for an influx of patients who didn't head the warnings, and looked at the eclipse without proper protection.
 "We were expecting we'd probably have maybe somewhere around 20, 25 people calling in the next day, so we had reinforcements for staffing. But, we've only had about three so far," said Jan Simpson, CEO of Spokane Eye Clinic.
The clinic credits that low number to awareness.
"I think our community did a fantastic job of educating people about how to safely view the solar eclipse," Simpson said.
Spokane Eye Clinic says there is still a possibility that symptoms of eye damage could take 48 hours to manifest. If you looked directly into the sun and start to experience vision problems, you should make an appointment with an ophthalmologist.